Automatic telephone-exchange for double-wire telephone systems.



No. 835,878. I PATENTED NOV. 13, 1906.

I G A. BETULANDER. AUTOMATIC TELEPHONE EXCHANGE FOR DOUBLE WIRE TELEPHONE SYSTEMS.

APPLICATION FILED APR. 5. 1904.

6 SHEETS-SHEET 1.

1 T fE W. 4w 1 A44 fil ctomuw I N0- 835,878. PATENTEDNOV. l3, 1906.

G. A. BETULANDER.

AUTOMATIC TELEPHONE EXCHANGE FOR DOUBLE WIRB'TBLEPHONE SYSTEMS.

APPLICATION FILED APR. 5. 1904.

6 SHEETS-SHEET No. 835,878. PATENTED NOV/13, 1906.

G. A. BETULANDBR.

AUTOMATIC TELEPHONE EXCHANGE FOR DOUBLE WIRE TELEPHONE SYSTEMS.

' APPLIOATIONIILED APR.6. 1904.

6 SHEETS-SHEET 4.

I'll Illll as.

PATENTED NOV. 13, 1906- No. 835,878. S k

G. A. B'BTULANDER. AUTOMATIC TELEPHONE EXCHANGE FOR DOUBLE WIRE TELEPHONE SYSTEMS.

APPLICATION FILED APR. 5. 1904.

6 SHEETS-SHEET 5.

M'h z earm- No. 835,878. PATENTED NOV. 18, 1906.

' G. A. BETULANDER.

AUTOMATIC TELEPHONE EXCHANGE FOR DOUBLE WIRE TELEPHONE SYSTEMS.

APPLICATION FILED APR. 5, 1904. I

6 SHEETS-SHEET 8 I l I I I I I I I I l Unrrnn 1 srnrns PATENT OFFICE.

GOTTHILF 'ANSGAR-IUS BETULA-NDER, or STOCKHOLM, SWE EN. AUTOMATIC TELEPHONE-EXCHANGE FOR DOUBLE-WIRE TELEPHONE-SYSTEMS.

Specification of Letters Patent.

Patented Nov. 13, 1906.

Application filed April 5, 1904. Serial No, 201.683.

1'0 all whom; it may concern.-

Be it known that'I, Gorrnrrr ANSGARIUS units-springs, so BETYJLANDER, a subject of the king of Sweden gether with the movable part carrying the caused to follow and Norway, and a resident of Stockholm, in fixed position with relation to said slides the Kin dom of Sweden and Norway, invented certain new and useful Improvements in Automatic Telephone-Exchanges for Double-VVire Telephone Systems,-of whid placed at subscribers.

the following is a specification, reference. being had therem to the accompanying drawln 's.

This invention .relates to automatic te ephone-exchanges for double-wire telephone systems of that kind where. an earth connect1on is employed at the exchange during all the time used in automatically establishing telephonic communication between telephone-stations in the same or diflerent communities and where a common battery the automatic telephone-exchange supplies the current for establishing the desired connections.

The invention more particularly relates to automatic telephone-exchan es of the kind described inmy application or Letters Patent, Serial No. 146,804,.filed March 9, 1903, and has for its object to provide means whereby the automatic telephone-exchange can be adapted for use in lar er telephone plants comprising any desire number of To this end the movable part supporting, the units-springs to bedescribed is provided with one. or severalconnectingslides'movable in their longitudinal direction,

and onl one of these slides is operated directly y the connecting electromagnet.

' The connection operation is performed in several distinct periods, and the slides are arranged in such a manner that during'the'first period of the connection operation only the slide operated directly by the connecting electromagnetis moved forward step by step until, after the end of the first period of the connection operation, it is connected to ether in a determined position with the second slide. Then during the second period of the connec tion operation these two slides are" moved forward in mutually-fixed positionsuntil, af-' ter th'e end of the second period oftheconnection operation, they are connected together with a third slide. Then during-the third period of the connection operation these three slides are moved forward inmutually- I fixed positions,- and so on. During the last but one period of the connection operation the whole system of slides is connected tohave ,* ation.

during the last period of the connection oper- Taking a subscribers number whatsoever-for instance, .4568the first figure 4 may belong to the first, the next figure 5 to the second, the next figure"6 to the third, and the last figure 3 to the fourth period of the connection operation. In this case after the first. period of the connection operation the thousand-slide is connected together in a determined position with the After the second period of. the connection operation these two slides are hundreds-slide.

connected together in a determined position with the tensslide, and. after the third period oft-he connectionoperation all these slides are connected together in a determined posi:

tion with the units-slide or the part carrying the units-springs.

In the drawings, Figure 1 is a diagram of a connecting apparatus adapted to be used in a telephone plant comprising two hundred and ninety-nine subscribers. Figs. 2 and 2* taken together constitute a diagram showing the arrangement of the contact-field and the connections between two subscribers. For instance, between thesubscriber No. 1 and that No.235. Figs. 3', 4, and 5 are diagrammatic views, the first showing oneslide,

the second showing three slides, and. the' third showing four slides. These views are merely to illustrate the application of'the invention to connecting apparatus having different numbers of slides.

that the said movable part is the system of slides in a Referring'first to Fig. 1, the arrangement at the substation is as follows: Interposed in each line branch 1 and 2 is a switch or circuit breaker 3 4, respectively, and a. contactpiece 5 6, respectively, for conn ecting the correspondingline. branch with the earth when required. One switch 3, hereinafter called the connecting-switch, is used for establishing the desired connections and the other switch 4, hereinafter called {the disconnecting-switch, for disconnection; Normallyi. e., when the telephone-receiver TR is hanging upon its hook H-the following parts are bridged between the line branches 1 and 2---yiz., switch 3, magneto-generator MG, signal-bell 3B, switchrhoo'k H, its lower-contact-anvil LC, and switch .4." The secondary winding SW of theinduction-coil and the miorophone-battery MB, the microphone M,

the primary winding PW'of the inductioncoil, the contact-spring CS, and the contact C is now broken, since the insulating-piece Y at the hook H keeps the contact-spring CS pressed down. \Vhen, however, the telephonereceiver- TR is removed from its switch-hook, the latter is pressed by its spring against the upper contact UC, by which the magnetogenerator MG and the signal-bell SB are short-circuited through the hook H, whereas the secondary winding SW of the inductioncoil and the telephone-receiver TR are bridged between the line branches 1 and 2. At the same time the primary circuit is closed through the contact-spring CS and the contact-piece C. The described arrangement at the substation is not essential, as it can be modified in several ways without departing from the spirit and scope of this invention; The connecting apparatus connected with the subscribers telephone apparatus com-' prises a connecting-electromagnet. 9, a disconnecting-electromagnet 10, a locking-electromagnet 11, whose armature 33 normally prevents the armature 22 'of the connectingelectroma net from being attracted by the latter, an a cut-out electromagnet l2, serving to prevent the units-springs during the connection operation from making contact with connecting-wires leading to the connecting apparatus of subscribers with which no connection is desired. Of the two line branches 1 2 the one, 1, is connected with the connecting-electromaghet 9, as, also, through a Wire 13 with one hundreds-spring 84, and the otherline branch 2 is connected with the disconnecting-electromagnet 10, as, also, through a wire 14 with another hundredssprin 85. The windings of the connecting and isconnecting electromagnets are connected together by a wire 17, and each of the I said windings is further connected by a wire 18 19, respectively, with a contact 20 21., respectively, as shown in the drawings. The armatures 22' 23 of the electromagnets 9 10 are electrically connected together by a wire 24 and further connected through the windings of the locking and cut-out electromagnets 11 12 and wires 25 26 with one pole'of the connecting-battery 27, the other pole of which is connected with the earth. In the form of embodiment of the invention shown in Fig. 1 there are two connectingslidesplacedon the connecting-bar 29. When the connectin apparatus takes up its reposing position, the two connecting-slides 71 72 re firmly coupled together with each other nd with the bar 29; but during the connection operation e slides are disconnected I and then coup ed together one after the other I with the slide, initiating the movement'until l at last the bar 29 is caused to move with the 1, slides. Only one slide 71 (that which is first i moved) is provided with connecting teeth, l preferably ten for each figure in the number indicating the whole number of subscribers. Thus in the case of nine hundred and ninetynine subscribers the slide 71 should have to the teeth of the bar 29, (the unitsslide,) those of the tens-slide 72, and those of the hundreds-slide71. In the case of nine thou sand nine hundred and ninety-nine subscribers the slide 71 should have forty teeth, and so on. In Fig. 1, also, the slide 72 and the bar 29 are shown provided with teeth, but these have a quite other object than the connecting-teeth of slide 71, as they form, to ether with the levers 73 and 75, to be descri ed, a

sort of clutch by which the parts 72 and 29 are united, one after the other, with the slide operated directly by the armature of the connecting-electromagnet 9.

As before mentioned, the connecting apparatus shown in the drawings is adapted for a telephone plant comprising two hundred and ninety-nine subscribers. It has two slides 71 72, one of which, 72, is movably mounted upon the bar 29 and the second, 71, movably mounted upon the first slide 72. Twoslides Will suflice up to nine hundred and ninety-nine subscribers. If it be desired to arrange the telephone exchange for nine thousand nine hundred and ninety-nine subscribers, three slides would be necessary, one slide movable along the bar 29, a second slide moving along the first one, and a third slide moving along the second one.

The armature 22 of the connecting-electromagnet 9 is provided with a feeding-pawl 28, or the like, engaging the notches oi' the slide 7].. The armature 23 of the disconnectingthat when the disconnecting-electromagnet tracted engages the notches of the slide 71 to prevent its falling down. -When the current ceases to flow through the electromagnets 9 10, the armatures 22 23 are retracted by their springs 31 32, respectively, in the positions shown in'the drawings.

The coupling arrangement for coupling together the slides 71 and 72 may consist, for instance, of a lever 7 3, pivotally attached to the slide 71, said lever having a hook-shaped end engaging a notch 74 in the slide 7 2, and the coupling between theslidc 72 and the bar 29' may consist of a lever 75, pivotally attached to the slide 72, said lever 75 having a hook-shaped end engaging a notch. 76 in the bar 29. Pivoitally attached to each of the levers 73 .75 is a catch 77 78, respectively, each catch being held by a spring 79 80, respectively, in a definite inclination to the corresponding lever 73 75, respectively. At-

electromagnet 10 carries a locking-pawl 30,

is energized and keeps its armature 23'at-,

three into ten or thirty teeth corresponding tached to the armature 33 of the lockin -electromagnet 11 are pins 81 82, normal y en-' gaged by the free hook-shaped ends of the catches 77 78. It will be seen from Fig. 1 that the hundreds-s1ide 71 does not carry any contacts The hundreds-contacts'are carried by the tens-slide 72 and the. tens-contacts by the units slide or-bar 29. The units-contacts are lying in the connecting-field behind the con- 'necting apparatus and are not movable. The

hundreds-springs 84 85 86, Fig. 2, movable along the'hundreds-contacts are attached to an insulating-plate 83, carried by the lever 73, and are raised and lowered with the hundteds -slide 71. The nine tens-springs 84 to 86?, movable along the tens-contacts, are attached to aninsu lating-plate carriedby the lever 7.5.and move up and down with the tens-slide 7 29. The umts-springs 849 to 86 are attached in groups or sets to an insulatin'g-piece fastened to thearmature 37 ofthe cut-out electromagnet 12, carried by the connecting-bar 29,- and are raised and lowered with the said bar. In the diagrams shown in the drawings illustrating the connecting'apparatus.- of a telephone exc'hange comprising two .hundredand ninety-nine. subscribers there are only four hundreds-contacts for each ofi-thc three hundreds-springs 84 to 86.

In every vertical column the undermost contact is a reposing contact. Thecontact next above the reposing contact is a; group 'contact of the first hundred, (one to ninety-nine.)

The neXt contact-is a'grou'p-contact of the second hundred,..(on e hundred to one hundred and ninety-nine,) and the uppermost contact is a group-contact of the third hun- 'dred, (two hundred to two hundred and ninety-nine.) Each'oi-the hundreds-cone.

. tacts. is connected through a conducting- .'vertical co1umns the lowermostcontaot is a! .repo sing contact, the contact'next above is a group-contact of the first ten, (one to nine,)

wire with one'of the tens-springs 84 to 86, respectively. Thetens-contacts. are also ar:

ranged in vertical columns, each column comprising eleven contacts. In each of "these the contact next .above is a'group-contact 'ofthe second ten, (.ten to nineteem) '&c., and the uppermost-contact is' a group-contact of the tenth, ten, (ninety to ninety-nine.) yEach tens-contact is connected- .through aficonducting wire with one of the units-springs 84 to 89?, respectively; The'units-contacts are also arranged in vertical columns." Each vertical column ofcontacts; corresponding to the springs8 i to 85, compriseseleven con-- tacts, and in each of thesecoluinns' of contacts the undermost contact isarepos'ing contact, the contact next above is a zero-f contact, the contact next aboveis a one contact, the contact next above 1s a two-' contact, &c., and thallpp rmost contact is a' nine-contact. The units-contacts are contablishing the following circuit: earth, bat- 1 tery 27, wire 26, wire 25, 'electromagnets 12 and'11- in series, wire 24, armature 23, contact 21, wire 19, from which the circuit divides into two branches, one comprisin the wire 17, electromagnet 9, line branc 1, switch 3, contact 5, electroma netE, (which is thus energized and closes t e contact 6,) and earth, the other comprising the electromagnet 10, line branch 2, switch 4, contact 6,.

and earth. The electromagnet 11 being energized,attracts its armature 33, thus releasing the armature .22, which is now attracted byits electromagnet 9. .The current from battery 27 then after having passed the elec tromagnet 11 divides in two branches, one comprising the armature 22, contact 20, wire 18, electromagnet 9, line branch 1, and earth, the other comprising the armature 23, contact 21, wire 19, electromagnet 10, line branch-2, and earth, the electromagnets'Q and 10 thus continuing holdingtheir armaturesin attracted positions. On account of the. electromagnets v 9 10 having attracted their armatures the feeding-pawl 28 has passed the uppermost tooth of the.slide 71 and entered into the notch beneath the said tooth, while the pawl 30 engages and aids in keeping the slide 71 in position. The lower end of the feedingpawl has now passed the upper end of the armature 23, .Whose upper en projects between-the slide 71 and the feeding-pawl 28." If the connecting-switch 3 is-now broken, the current from battery 27 ceases to flow through the electromagnet),

and the armature 2 2, withits feedingj-lpawl 28,

is. retracted by the spring 31, w ch now raises the slide .71 a distance corresponding to the length of a tooth equal to the vertical distance between the several contacts at the connectin apparatus. As the armature 33 of the loc ing-electromagnet 11. iskeptattracted during the whole-period of the conncction operation, the levers. 73 and 75 are.- withdrawn fromengagement with the slide .72 and bar-29,-,respectively, so that only .the slide 71 is lifted When the slide 71 is raised, the end of the pawl 30 slips over a tooth at, the said slide and enters the notch nearest below that toothffi'ius holding the-slid-in its 4 III raised position when the connecting-switch 3 again closes the circuit through the electromagnet 9.

It follows from the. preceding that if it be desired to raise the slide 71, say, four teeth four interruptions are to be made with the switch 3, the earth-contacts 5 6 being broken before the switch 3 is allowed to return and make contact after the fourth interruption. On account of the break at the earth-contacts 5 6 the battery 27 ceases to supply current to the electromagnets, and the armature 23, with its awl 30, is brou ht out of en a e P g g g ment with the slide 71, which is now kept in its raised position only by pawl 28.

In order to further explain the connection operation, it may be supposed that the subscriber No. 1 (or, as we will hereinafter call it, 001) wishes to ut himself in communication with the su scriber No. 235. He then by closing one of the earth-contacts 5 6 at his telephone apparatus, rotating his magneto'-generator MG, opening the connectingswitch 3, closing the same, opening the con-' necting-switch for the second time, closing it again, opening it for the third time, breaking the earth-contacts 5 6, and closing the connecting-switch causes the hundreds-slide 71 to be fed three steps forward. When the armature 33 is attracted, the pins 81 82 cause the catches '7 7 7 8, pivotally attached to the levers 73 75, respectively, to move to the left, whereby the said levers 73 are caused to swing about their fulcrums, so that the lever 73 is withdrawnfromthe undermost notch 74 in the slide 72 and the lever 75 isv withdrawn'from the undermost notch 76 in the bar'29, by which the slide 72 and the bar29 are released from engagement with the-slide 71. At the same time the three hundredssprings 84 to 86 are brought out of engagement with 1 their contacts, which prevents any wear of the contact-sprlngs and contact-v pinsas also forming ofarcs between adjacent By means, of the three 1m-' electromagnet 11 is excited throughout the said period bythe current through 27,12, 11', 21, 1.0, 2, 4, 6, and earth. I

It will be seen that during the forward movement of the slide 71 the catch 77 swings about the pin 81 as a'fulcrum, but is not released before the end of the first period of the connection operation,when the circuit of the cr'mnecting-battery 27 is opened at the earthcape from the path of the pin 81.

' their respective contacts.

mature 33. As soon as the armature'33, on

account of the electromagnet 11 having been deprived of current, is retracted by its spring and-the catch 77, released. by the in 81, has

s rung upward the lever 73 um er the 1n-- uence of its own weight (or of a s ring) catches into the slide '72 but as the slide 71 has been raised a distance equal to three teeth the lever 73 now catches into the fourth notch 74 ofthe slide 72 and keeps the two slides 71 and 72 firmly united in such 'osition. The slide 72 having not been raisedz'the lever 75, when the armature 33 is retracted into its resting position, again catches into the undermost notch of the bar 29.

The subscriber No.- O01 now during the second period of the connection operation produces afour-step movement .of the slide 71 by making three breaks (instead oftwo) at the switch 3. The armature 33 is attracted as before, and the pin 82 takes the catch 78, attached to the lever 7 5, with it, so that the said lever is caused to swing about its fulcrum and leaves the undermost notch influenced on account of the spring 79 having caused it, after the armature 33 was retracted and the said catch released by the pin 81, to swing upward, and thereby to es- Thus the bar 29 is left .in its resting position also during the second period of the connection operation, while the slides 71 and 72 are kept together by lever 73 in the relative position determined during the first period of the connection operation. At the same time the nine springs 84" to 86 are removed from By means of the four current impulses the slides 71 and 72 are to ether brought four -steps forward,

while t e bar 29 remains at rest on account of the catch 78 retaining its engagement with pin 82 of the armature 33 during the whole period of the connection operation. After the end of the second period of the connec tion operation the armature 33 returns to its reposing position, whereby the pin 82 releases the catch 78, which is then caused by its spring 80 to recover its original inclination with respect to lever 75. now been lifted a distance equal to seven teeth, while the slide 72, which is now joined with the slide 71, but which. did not move during the first period of the connection op- 7 6 of the bar 29, whereas the catch 77 is not The slide 71 has nine.) about the foot.) During the last period of the connection operation the subscriber No. .5

001 effects a six-ste movement of the slides and. bar. The who e system of slides being now oined together, the hlmdreds-springs 1 and tens-springs remain pressing against their resent contacts, while the units-springs are rought to bear on the fives-contacts. (See Fig. 2.) The subscriber No. 001 has now brought himself in connection with the de 3 sired-subscriber No. 235. The speaking-circuit is the following: telephone apparatus of the subscriber No. 001, line branch 1, branch 13 group-spring 84 of the corresponding connecting apparatus C, (Fig. 2', left-hand side,) group-contact of the third hundred, roupspring 84, group-contact of thefourt ten,

branch .13, line branch 1 contact-spring 84, corresponding fives-contact of t the units-spring 8 1 at e unit group, re osing contactof paratus D of subscriber N0. 235, spring 84*", reposing contact of spring 84 spring 84, reposmg-contactof spring 84, spring 84,

of subscriber No. 235, telephone apparatus, linej branch 2,

branch 14, spring -'85, reposing contact,

ine 85*, reposing contact, spring 85:10 PQ mg contact, sixth contact of s i 503' at the connecting apparatus of subscriber 2, back tothe tel N o. 001, spring 85, fourth tens-contact of spring 85, spring 85 ,third hundreds-contacts of spring 85, s'pr n '85, branch 14, line branch ephone apparatus of sub scriber No. 001..

In case the subscriber 235 desires to make connection 'with subscriber 001, be during the first period of the connection apparatus eflects a one-ste movement; Thenduring the second perio of the connection operation a new one-stepmovement and, finally, during .the'third period of the connection operation-a two-step movement of slide 71., The connection in this case is'to be seen'in Fig. 2.

. a All these movements of connection are au- 'xtom'atically performed by means of a controlling apparatus at the substation, so that the tsub'seriber has only-to turn a hand or pointer and needs not think of the various -makes and breaks of circuits. 1. v

' The operation of restoring the. connecting apparatus after the conversation is finished t e connecting apwhichisthus held in osition 0 1s performed-by closing one of the earthcontacts 5 or 6, rotatingthe magneto-generator to send out an alternatingcurrent, breaking the disconnecting or restoring switch 4, breaking the earth contacts 5 and 6, and closing the'switch 4, whereby the slides 71 72 and bar 29 fall directly down in their lower most or original positions. It will be understood that when the disconnecting-switch 4 is opened the disconnectingelectromagnet is deprived of current, whereby the arma-- ture 23 is retracted, said armature withdraw-' ing the pawl 28 from engegement with the teeth of the slide 71, set atthe whole system of movable parts falls down on account of it being not longer supported bypawl 28,

: whereby the hook-shaped lower endof the lever? 3 glides down along the teeth 7 4 of the slide 72, and the hook-shaped lower end of lever 75 moves along theteeth76 of bar 29. As soon as the slides 71 and 72 and bar 29 reach their lowermost positions the catches 77 78 again take up their original positions withrelation to the pins 81 and 82- 11. 6.,17111 free hook-shaped end ofthe catch 77 engages the pin 81 and that of catch78 engages pin 82. It is clear thatafter the connection 0 era tion has been performed a-calling-signa is tr be given byrotating the magnetosgenerator r inform the called subscriber that a conversa tion is desired. The earth-contactsf5and l;

then being opened, the armature 33 of the electromagnet 11 is not attracted, and a'fur her movement of the slide system is therefore prevented. w

The connection operation is thus performed in the follo, way:

two earth contacts 5 or 6. Second, rotating the magneto-generator: electromagnets 9 and I. First pem'0d.F1rst, closing one ofthe 10 excited, contact 21 closed, thusfa circuit from battery27 through magnets 12 and 11 in series and magnets 9 10 in parallel closed,

the other of the two earth-contacts 5 and 6 automatically closed armature 33 attracted (by which lever f7 3 is withdrawn from engage-' ment with slide 72 and lever 75 is Withdrawn from engagement with bar 29, so that the said slide 72 and bar 29 are disconnected from slide 71,) armature 22 attracted, pawl 28 "under the next 'tooth of slide 71.-

breaking switch 3: line branch 1 and mag.'

ived of current, armature 22 re- Third,

net 9 deplr tracted, t ereby lifting the slide 71 one tooth, (repeated at every break at 3.) Fourth,

breaking the earth-contacts 5 and 6 while still keeping [switch 3 opened: all the magnets deprived of current, armature 23 retracted, pawl '30 therebyleavin 'slide 71,

28, catch 77 released orn enga'gementwith armature 33 and raised by its spring 79 into its original inclination, lever 7 3 engaging slide 72 in its raised posltion, lever 75 enga'ging, as

before, the nndermost notch of bar 29.

y y p w vII. Second period -Fifth and sixth, clos- I one of theitwo earth cpntaets 501-5 and ing the earth-contacts 5 and 6 while still keeping switch 3 opened: all the magnets deprived of current, armature 23 retracted, pawl thereby leavin slide 71, which is again held in position only by pawl 28, catch 78 released from engagement with armature 33 and raised by its spring 80 into its original inclination, lever 75 engaging bar'29 in its raised position.

. II L Third period-Ninth and tenth, closing one of the two earth-contacts 5 or 6 and rotating the magneto-generator result as under first and second, with the difference that when the armature 33 is attracted the slides 71 and 72 and bar 29 are still kept united together. Eleventh, breaking switchl3: line branch 1 and magnet 9 deprived of current, armature 22 retracted, thereby raising the slides 71 and 72 and bar 29 one tooth, (repeated at every break at 3.) Twelfth, breaking the two earth contacts 5 and 6 while still keeping switch 3 opened: all the magnets deprived of current, armature 23 retracted, pawl 30 thereb leaving slide 7 1, so that the whole system 0 slides is supported only by pawl 28. Thirteenth, calling the desired subscriber by the magneto-generator, magnets 9 and 10 excited, but without result, because the return-conductor to the connecting-battery 27 is broken.

After the conversation is finished.-f-Four- .teenth and fifteenth. Closing one of the two earth contacts (5 or 6) and rotating the mag. Result as under ninth and neto-ge'nerator. tenth. Sixteenth. Breaking switch 4: magnet 10 deprived of current, armature 23 retracted, wherebythe upper end of said armature withdraws the pawl 28- from engagement with slide 71', so that the whole system of Slides falls down in its original position.

In the automatic telephone-exchange illustrated in the drawings an arrangement is tion between two subscribers.

provided for preventin any third subscriber from disturbing or ovei'hearing the conversa- This arrang'ement comprises a number of unitssprings 86 to 86 86* to 86, and 86 to 86, each of said springs'being suitably provided with a roller at one endand connected at'the 'other end through a tens-contact, spring 86, 86 86, "respectively, hundredscontact, and spring 86 with aspring 40 entering'bet'ween two contact-anvils 41 and 42, one of which, 41, is connected with one pole of a cut-out batt'e'ry 45, while the other contact-"anvil 42 is connected through the cut-- out electromagnet 12 with the other pole of the said battery 45. The spring 40 normally bears. on contact-anvil 41, but is. attracted when the electromagnet 12 is excited against the contact-anvil 42. The springs 86' to 86, 86* to 86* and'86 to 86 normally bear on no contact; but when the bar 29 is raised one tooth each of the said springs will bear on a zero-contact, and when the bar 29 is'raised' one more tooth'they will bear on a ones-contact, and so on, so that when the bar 29 is raised a distance equal to ten teeth they will bear on a nines-contact. Each units-contact of one connecting apparatus is. connected with the corresponding units-contacts of the other connecting apparatus. Placed upon the connecting apparatus are, further,

two springs 49 50, one of which, 49, is connected through wires 51 and 44 with the battery 45 and the other, 50, through a wire 52 with one of the cut-out wires. The slide 71 further carries a knob 53, or the like, of insulating material, said knob having such a position that when the slide 71 takes up its lowest position, (see Fig. 1,) the springs 49 50' are ept apart bythe knob 53, whereas when the slide 71 is raised the knob 53 leaves the spring 50'and allows the latter to make contact with the spring 49. If now, as described, subscriber 001 has connected himself with subscriber 235, these two'subscribers cannot be disturbed by a third subscriber; Suppose, for instance, a third subscriber wishing to put himself in connection with-subscriber'235 after the connection between sub scribers 001 and 235 has been performed.

The third subscriber then has to bring his connecting apparatus into the same position as that of the connecting apparatus C, (Fi 2, left-hand side.) During the three perio s of, the connection operation the electromagnet 12 keeps its -armature attracted so that at the connecting apparatus of the third subscriber spring 40 bears on contact-anvil 42.

The units-springs 84 to 86arethus kept ICC out of contact with the wire leading to the def sired subscriber. When the connection operation was performed, the armature 37 at the connecting apparatus of'the third subscriber, in case subscriber 235 was not busied, would be retracted into its resting position on account of the circuit of the connectingbattery 27 being broken at the earth-contac'ts 5 and 6 of the third subscriber, and the.

connecting-springs would then come in coir-j tact with, their connecting-wires, respectively; -In the present instance, however, this is not the case on'account of the following circuit of the cut-out battery 45 being 2 closed. First, following parts of the connect ing apparatus of the third subscriber: elec-' tromagnet 12, contact-anvil 42, sprin .40, spring 86, group-contact of the third undred, spring 86, group-contact of the fourth ten, spring 86, then through the corregig O.

name

sponding cut-out wire, and, second, following parts of the connecting apparatus C spring 86 group-contact of the. fourth ten, spring 86", group-contact of the third hundred, spring 86, spring 40, and contact-anvil 41, back to battery 45. The electromagnet 1 2 of the third subscriber is thus still supplied with current, but now from battery 45,

which is sending current through electromagnet 12 in the same direction as before the connecting-battery 27. A third subscriber therefore, cannot disturb the convergroup-contact of the first ten, spring 86,

cut-out wire, and, second, following parts of the connecting apparatus C": Springs 50 and 49 -back to battery 45. It will thus be found that the connecting apparatus 0, that hasestablished the connection between the substations 001 and 235, connects that pole of the battery 45 which is not connected with the electromagnet 12 partly through contactanvil 41, spring 40, spring 86, group-contact,

spring 86, group-contact, and spring 86 with a cut-out wire entering the connecting apparatus D of the desiredsubscriber 235 and partly through the cut-out spring 49 50 with the cut-out wire of the connecting apparatus that establishes the connection, thus preventing all other subscribers from connecting themselves with any of the two subscribers connected to ether for conversation.

The constructions illustrated in Figs. 3, 4, and 5 will. not require special description except to state that Fig. 3 shows a construction where but one slide is employed, Fig. 4 illustrates a construction where three slides "are emploied, and Fi 5 illustrates a construction W ere four slides areemployed. In Fig. 3 the slide is designated by the numeral 72. In Fig. 4 these features are designated by the numerals 72, 71,-and 71*. In Fig. 5 they are designated by the numerals 72 71 71 71.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. An automatic double-wire telephone system comprising a movable part, a slide arran ed to move in the direction of movement of t e-"said movable part, means for causing thelslide to move step by step, in the directlon' of movement of the movable part during the first eriod of the connection operation, means or connecting together the slide and the movable part in a fixed position with relation to each other, means for feeding forward the 'slide together with the movable part connected therewith in the same direction of movement during the second period of the connection operation, and means for restoring the slide and the movable part to their initial positions, substantially as described.

2. 'An automatic double-wire telephone system comprising a movable part, a slide movable along the said movable part, a second slide movable along the first slide, means for causing the second slide to movestep by step along the first slide during the first period of the connection operation, means for connecting together the slides, means for causing the slides to move together step by step along the movable part during the second period of the connection operation, means for connecting together themovable part with the two connected slides, means for feeding forward the slides and the movable part in fixedv positions with relation to one another during the third period of the connection operation, and means for restoring the slides and the movable part to their initial positions, substantially as described.

3. An automatic double-wire telephone system comprising a movable part, a slide movable along the said movable part, a second slide mogable along the first slide, a third slide movable along the second slide, means for causing the third slide to move step by step along the second slide during the I first period of the connection operation,

means for connecting together the second slide with thethird slide, means for causing the two connected slides to move step by step along the first slide during the second period of the connection operation, means for connecting all three slides together, means for causing the three connected slides to move step by step alon the movable part during the third period 0 the connectiono eration, means for connecting together t e movable part with the three connected slides,

means for feeding forward the slides and the movable part in fixed positions with relation to one another during the fourth period of the connection operation, and means for restoring the slides and the movable part to their initial positions, substantially as described.

4. An automatic double-wire telephone system comprising a movable part, a .slide IIC movable along the said movable part, a second slide movable along the first slide. a third slide movable along the second slide, a fourth slide movable along the third slide, means for causing the fourth slide to move step bystep along the third slide during the first period of the connection 0 eration, means for connecting together the t 'rd slide with the fourth slide, means for causing the two connected slides to move'step by step along the second slide during the second eriod of the connection operation, means or connecting together the second slide with the two connected slides, means for causing the three connected slides to move step by step along the first slide during the third period of the connection operation, means for connect- 1 ing all four slides together, means for causing the four connected slides to move step by I step along the movable part during the fourth period of the connection operation,

ablepart in fixed positions with relation to one anotherduring the fifth period of the connection operation, and means for restoring the slides andthe movable part 'to their initial positions, substantially as described. In witness whereof i have hereunto signed myname in the presence of two subscribing witnesses.

GOTTHILF AXSGARIL'S BETL'LANDER. \Vitnesses:

RoBER'r APELGREX, AUG. SORENSEN. 

